MASH how would one create a growing group of cells on a flat surface

[sulkybunny]

i am trying to create a cell growth animation. starts with 1 and a whole community grows from the same point.. 

tried volume point distribution animating the amount... but struggling to get the cells to stay flat on a surface (obviously after adding dynamics to calculate collisions they pile on top of each other.. )

tried all sorts of things.. constraints..   the problem is that the next cell is generated it pushes the previous one in a random direction.. 

any ideas?

[mspeer]

Hi!

Distribute on a mesh (plane), then animate visibility with an animated texture.

[sulkybunny]

interesting idea.. didn’t think about that one.. my new cells are growing into a group of existing cells (should have mentioned it!! 🙂 ) so they need to push the old ones away (like cancer cells) i wonder if this technic will still push the old ones dynamically.. i am trying to simulate growth of cancer cells into a healthy group of cells.. and am after that nice dynamic reactions and moments..

ill give this idea a go any way! thanks 🙂

[djonesuk]

Have you looked into the MASH World node?  It can do automatic collision separation. 

Here I used 2 points per cluster and animated a volume point distribution from 1-50 points.

[sulkybunny]

thanks man...  

i tried world..  my main issue with it is that every new cluster is in a completely different position.. creates a sort of noise ... one can't follow whats going on.. if you know what i mean..   

so far my best results are to press those cells between two colliders.. floor and ceiling..  so they stay flat.. u can see in my video that ur eye can nicely follow what happens so it doesn't turn noisy like the world node... how ever.. it feels like  a cheat.. i would love to find  way to stick those cells to any surface..    i was hoping a sort of constraint will work.. still thinking about it..  i tried closest point on mesh from offset node.. but dynamics ignore it...    i would love to be able to replicate this on a curved wall or un even surface..   

Screencast will be displayed here after you click Post.

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[Anonymous]

This might get you a little closer. Scene attached (Maya 2018.2)

Using your idea of a Volume > Point Distribution with a sandwich to control the cells.

All I've really added is the idea of MASH Bias. MASH Bias is a way to determine whether MASH or Bullet is in charge. On the Dynamics node if you set this to 100 (play with the value - it can go above 100) it puts MASH 'in charge' (a value of 0 means Bullet is in charge). You can use it as a switch to turn Dynamics on half way through sims. Some examples here - https://www.mainframe.co.uk/bash (there's a link to download scene files)

You could use the Ray Cast feature on the Offset node (new in 2018.2) but you'll find some points may sometimes jump up on top of the others.

Hope that helps?

Chris

[Anonymous]

Or...just thinking about this again...you could go even simpler and just use a radialField?

Drop the Offset, set MASH Bias back to 0

Create a radialField (Fields/Solvers > Create > Radial)

Set it to say -10 Magnitude

Drag that into the Fields section on the MASH Dynamics node.

That will prevent some of the noise you sometimes get with MASH Bias.

[sulkybunny]

Thanks a lot Chris i will check this carefully

when u say ray cast.. do u mean the closest point on surface option on the offset node?  i tried it but the dynamics seems to ignore it.. the best i could do was the cells stuck to the surface but then drifted off... how ever.. maybe a combination of the Bias (which i was aware of) and  the radial force (which i didn't think about and sounds like a great idea )  i do have two MASH  networks  interacting.. (one existing cells and the other growing...) ill see how they both react to this force..

thanks 🙂

[Anonymous]

Yep, Ray Cast is new in 2018.2 under the Closest Point on Mesh settings but
that method will only work in combination with a bit of MASH Bias.

The Radial Field set up is definitely my favourite visually but that's
dependent on the final result you're after of course 😉 The other nice
thing about it is it should work on uneven surfaces too assuming you can
position it so the field's force pulls in the right direction for your
surface.

[sulkybunny]

hi Chris

only the flight node seem to have a field section...  can one hook up any dynamics sim to a force field?

[sulkybunny]

Hey Chris. i agree the radial force is an elegant solution..  its a pity you can't control which mash network it effects... as i have one very tidy grid of cells - network 01 (healthy cells) and one growing Network 02.. my worry is that the field will pull in the grid and get it out of alignment..  i will defo give it a go. maybe the collision will keep the grid somehow steady.. 

what MASH should really have is a "make soft" node...  imagine controlling which parts of the network are soft with a fall off object!! 

[Anonymous]

Does your second network (grid) need to be dynamic? If not, you could just use the ReproMesh of your grid network as a collider (you'll need to be in Repro (mesh) mode and not the instancer for the grid network).

[sulkybunny]

Yeah the grid has to be dynamic as it’s disturbed by the growth... you know .. the area around the growth shuffle and move away..

The best results I get so far is the sandwich method 🙂 on vertical surface I just turn off gravity .. and bringing down max velocity on mash make it all kind of stay ..

I wish there was a “sticky” attribute .. like N particles

[Anonymous]

A bit of MASH Bias on your grid might help with that too.

[djonesuk]

Just a point of clarification, the fields section is on the BulletSolver not on the Dynamics node.

[Anonymous]

Typo but I can't seem to edit my post. Good spot 😉